In recent years, a battery in which carbon material such as graphite is used as a negative electrode material and a lithium-containing metallic oxide such as LiCoO2 is used as a positive electrode material has been suggested. The battery is called a rocking chair battery in which after assembling cells, lithium ions are supplied from the lithium-containing metallic oxide of the positive electrode to the negative electrode by charging the cells and during discharge, the lithium ions of the negative electrode are transferred back to the positive electrode. In other words, the battery is called a lithium-ion rechargeable battery in which only the lithium ions are involved in the charge and discharge without using metallic lithium in the negative electrode, and is distinguished from a lithium battery using the metallic lithium. The battery is characterized by high voltage, capacity, and stability.
With environmental issues coming to the forefront, a storage system for clean energy obtained by photovoltaic power generation or wind power generation or a power supply for an electric vehicle or hybrid electric vehicle substituting for a gasoline vehicle is being developed. As vehicle mounted apparatuses or equipment such as power windows or IT-related machines recently have high performance and high function, a new power supply is needed in view of energy density and output density.
As an electric storage device that responds to such applications that necessitate high energy density and high output characteristics, recently, an electric storage device called a hybrid capacitor in which electric storage principles of a lithium ion rechargeable battery and an electric double layer capacitor s gathering attention. As one of the hybrid capacitors, an organic electrolyte capacitor has been suggested, which uses for a negative electrode a carbon material capable of significantly increasing energy density by allowing the carbon material that can store and release lithium ions to store and carry (hereinafter, in some cases, referred to as “pre-doping”) the lithium ions chemically or electrochemically in advance to thereby lower a negative electrode potential.
Recently, the demand for a high capacity organic electrolyte capacitor with improved stability which has higher energy density and output density gradually increases, and particularly, the demand for a lithium ion capacitor which may be used in the range of 4.2 V to 4.4 V has gradually increased, but a research on the capacitor is not actively being conducted.
Therefore, it is urgent to develop a 4.2 V to 4.4 V lithium ion capacitor having high energy density and output density.
A coin type battery is useful in terms of utilization and basically has a two-electrode structure. Therefore, there is a problem in that after a complicated pre-doping process, a process of disassembling a battery to remove a lithium metallic electrode and reassembling the other electrode is required in a manufacturing process.